class_docstr: Memory wrapper.
code: def __str__(self):
      return "MemoryWrapper(%s)" % str(self._batch_env)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import math
  import os
  from tensor2tensor.layers import common_layers
  from tensor2tensor.models.research.rl import get_policy
  from tensor2tensor.rl import ppo
  from tensor2tensor.rl.envs.tf_atari_wrappers import StackWrapper
  from tensor2tensor.rl.envs.tf_atari_wrappers import WrapperBase
  from tensor2tensor.rl.policy_learner import PolicyLearner
  from tensor2tensor.rl.restarter import Restarter
  from tensor2tensor.utils import trainer_lib
  import tensorflow.compat.v1
  import tensorflow_probability
label_desc: Use image node_id 2 for calling the _MemoryWrapper obj's underlying member method code with example usage: obj.__str__() and returns: unknown